Grimnir (Valentine)/Strategy

Strengths

• His guaranteed triple attack effectively makes multi attack rate debuffs have no effect on him.
• Has a lot of damage instances both in his auto attacks and his skill casts making him synergize very well with Supplemental DMGDMG dealt is supplemented
  .
• Capable of increasing his and his party's offensive damage output.
• One-turn cooldown on all of his skills, which makes him a good skill-based damage dealer.
• Is capable of massive amounts of damage as well as debuffing foes that decrease the overall damage output of the enemy. The amount of damage it can deal can compensate the lack of damage on his charge attack.

Weaknesses

• Is not able to deal any damage through his charge attack.
• Outside of KeenSupplemental DMG to critical hits
  and Holy Rays of PurgationFoes and allies can deal critical hits regardless of element / DMG is supplemented
  Duration: IndefiniteField effect
  Local status effect, he lacks any other self-buffs that can utilize his multiple damage instances.
• Lower charge bar gain means he won't be using his charge attack that often. However, his guaranteed triple attack often compensates for it.
•  Holy Rays of PurgationWhen the binds on my right arm are undone... The heavens will tremble! The earth will quake! Myriad evils shall be brought to righteous end!
  (Deploy the Holy Rays of PurgationFoes and allies can deal critical hits regardless of element / DMG is supplemented
  Duration: IndefiniteField effect
  Local status effect field effect.)
  (Consumes 10 CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
  lvls.) allows the enemy to deal more damage and has a long ramp up time, the latter creating scenarios where players have choose to either use said skill or  Divine Tempest20-hit, 150% Wind damage to random foes (Damage cap: ~80,000 per hit).
  Inflict ATK DownATK is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, DA DownDouble attack rate is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, TA DownTriple attack rate is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, and Unbridled StormAttacks and special attacks have a chance to miss
  Base Accuracy: 150%Duration: 5 turns.
  (Consumes 7 CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
  lvls.).

Character Synergy

Grimnir (Valentine) benefits well from characters that give either Supplemental DMGDMG dealt is supplemented
or Bonus DMGDeals bonus DMG for one-foe one-ally attacks
. He also benefits from an increased skill cap so that  Dazzling Flair6-hit, 150% Wind damage to random foes (Damage cap: ~55,000 per hit).
Raise CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
Duration: Indefinite lvl by 1 (Max: 10). and  Divine Tempest20-hit, 150% Wind damage to random foes (Damage cap: ~80,000 per hit).
Inflict ATK DownATK is lowered
Base Accuracy: 200%Duration: 5 turnsLocal status effect, DA DownDouble attack rate is lowered
Base Accuracy: 200%Duration: 5 turnsLocal status effect, TA DownTriple attack rate is lowered
Base Accuracy: 200%Duration: 5 turnsLocal status effect, and Unbridled StormAttacks and special attacks have a chance to miss
Base Accuracy: 150%Duration: 5 turns.
(Consumes 7 CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
lvls.) would deal much more damage.

• Anila (Summer): guarantees Bonus DMGDeals bonus DMG for one-foe one-ally attacks
  in the form of  Sunny Summer Sheep-Shift10% Bonus Wind DMG effect to Wind allies' triple attacks., as well as  Puffy Summer TowersGrant an ally 30% Bonus Superior Elemental DMGDeals bonus superior element DMG for one-foe one-ally attacks
  Strength: 30%Duration: 3 turns and Dodge All (1 time)Takes no DMG or debuffs while in effect for a set period
  Duration: Indefinite. being another potential source of Bonus DMGDeals bonus DMG for one-foe one-ally attacks
  .  All of Creation6-hit, 100% all-elemental damage to all foes (Damage cap: ~100,000 per hit~600,000 total).
  Inflict all-elemental DEF Down10% Fire DEF DownDEF is lowered for fire DMG
  Strength: 10%Base Accuracy: 85%Duration: 180 seconds
  10% Water DEF DownDEF is lowered for water DMG
  Strength: 10%Base Accuracy: 85%Duration: 180 seconds
  10% Earth DEF DownDEF is lowered for earth DMG
  Strength: 10%Base Accuracy: 85%Duration: 180 seconds
  20% Wind DEF DownDEF is lowered for wind DMG
  Strength: 20%Base Accuracy: 100%Duration: 180 seconds
  10% Light DEF DownDEF is lowered for light DMG
  Strength: 10%Base Accuracy: 85%Duration: 180 seconds
  10% Dark DEF DownDEF is lowered for dark DMG
  Strength: 10%Base Accuracy: 85%Duration: 180 seconds. Also helps in accomplishing  I Lied, I Really Wanna Do Valentine's!Raise CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
  lvl by 1 at end of turn when allies deal damage 30 or more times to the current target in 1 turn..
• Andira: Is an all around great character that can give Grimnir (Valentine) Bonus DMGDeals bonus DMG for one-foe one-ally attacks
  through  Sage of EternityGrant an ally Shield (2500)Next ATK received will be ineffective for a fixed amount
  Strength: 2500Duration: 3 turns for 3 turns and Full Hostility100% chance to be targeted by one-ally attacks (Can't be removed)
  Duration: 1 turn Full hostility has the same properties as Substitute, but has lower targeting priority than Substitute for 1 turn.
  At level 75:
  Shield endurance increased to Shield (3500)Next ATK received will be ineffective for a fixed amount
  Strength: 3500Duration: 3 turns.
  At level 90:
  Shield endurance further increased to Shield (4000)Next ATK received will be ineffective for a fixed amount
  Strength: 4000Duration: Indefinite and now has indefinite duration.
  Also grants 30% Bonus Wind DMGDeals bonus wind DMG for one-foe one-ally attacks (Ends upon taking DMG)
  Strength: 30%Duration: Until hit (Ends upon taking damage).. She can also give him LoopATK is boosted / DEF is boosted / Double attack rate is boosted / Triple attack rate is boosted / Debuff success rate is boosted
  Level 100:
  After 2nd cast: Critical hit rate is boosted
  After 3rd cast: DMG cap is boosted
  Level 100:
  Can't be removed, increasing his damage potential as well as increasing debuff success rate on the debuffs of his  Divine Tempest20-hit, 150% Wind damage to random foes (Damage cap: ~80,000 per hit).
  Inflict ATK DownATK is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, DA DownDouble attack rate is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, TA DownTriple attack rate is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, and Unbridled StormAttacks and special attacks have a chance to miss
  Base Accuracy: 150%Duration: 5 turns.
  (Consumes 7 CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
  lvls.).
• Lecia (Grand): Can provide 50% Bonus Wind DMGDeals bonus wind DMG for one-foe one-ally attacks
  Strength: 50%Duration: 2 turns, 30% DMG Cap UpMaximum amount of DMG that can be dealt per hit is boosted
  Strength: 30%Duration: 2 turns, and 30% Wind ATK UpWind ATK is boosted
  Strength: 30%Duration: 2 turnsStacking: Unique through her  Stalwart CommandGain Issue OrdersIssuing orders (Order type is determined by the first ally skill used)
  Duration: IndefiniteCan't be removed. Orders lvl rises by 1 depending on the type of skill an ally uses. Skill cooldown set to 1 turn. (Recast skill to end orders.)
  On recast: Consume all Order stacks and provide an effect depending on Order type. Skill cooldown set to 3 turns., as well as Grimnir (Valentine) providing another way of increasing ATK OrdersIssuing orders (Boost increases with each ally DMG skill used)
  Can't be removed Attack Order stacks quickly due to  Dazzling Flair6-hit, 150% Wind damage to random foes (Damage cap: ~55,000 per hit).
  Raise CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
  Duration: Indefinite lvl by 1 (Max: 10). having one turn cooldown.
• Scathacha: Provides Bonus DMGDeals bonus DMG for one-foe one-ally attacks
  to allies with ShieldNext ATK received will be ineffective for a fixed amount
  through  Eternal WisdomBoost to Scathacha's ATK and multiattack rate when buffed by Wind ATK UpWind ATK is boosted
  .
  At level 95:
  10% Bonus Wind DMG effect to allies with ShieldNext ATK received will be ineffective for a fixed amount
  ., in which ShieldNext ATK received will be ineffective for a fixed amount
  can be attained by both characters.
• Yuel (Summer): Grants Supplemental DMGDMG dealt is supplemented
  through  ZuigetsuSupplement all allies' damage against foes with FoxflameSlight chance for attacks to miss / HP is lowered on every turn
  Local status effect. as long as the foe has FoxflameSlight chance for attacks to miss / HP is lowered on every turn
  Local status effect. Additionally supplies Bonus DMGDeals bonus DMG for one-foe one-ally attacks
  to all allies upon charge attack.
• Tiamat: Can provide skill damage and skill damage cap to allies based on the amount of Typhoon CrestWind magic is amplified (Max: 5 / Can't be removed)
  s they have through  Anima DuctusAmplifySeraphic modifier damage against Earth foes by 20%.
  At level 95:
  When Tiamat is a main ally: Also amplifiesSeraphic modifier other Wind allies' damage against Earth foes by 20%.
  Boost to Wind allies' skill specs based on their number of Typhoon CrestWind magic is amplified (Max: 5 / Can't be removed)
  .
  (Boost to skill damage specs takes effect even when Tiamat is a sub ally.) once she reaches level 95.

Weapon Synergy

Given the fact that his skillset leans towards the ability to deal critical hits, he works well with critical-based builds, such as Last Storm Harp. He will also benefit from Weapons with Skill Damage Cap as two of his skills deal a good amount of skill damage. One type of weapon we will greatly benefit, however, is any weapon that gives him any type of Supplemental DMGDMG dealt is supplemented
. Some notable examples are:

• Ewiyar's Beak: is capable of increasing the damage  Dazzling Flair6-hit, 150% Wind damage to random foes (Damage cap: ~55,000 per hit).
  Raise CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
  Duration: Indefinite lvl by 1 (Max: 10). and  Divine Tempest20-hit, 150% Wind damage to random foes (Damage cap: ~80,000 per hit).
  Inflict ATK DownATK is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, DA DownDouble attack rate is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, TA DownTriple attack rate is lowered
  Base Accuracy: 200%Duration: 5 turnsLocal status effect, and Unbridled StormAttacks and special attacks have a chance to miss
  Base Accuracy: 150%Duration: 5 turns.
  (Consumes 7 CycloneConsumed by Grimnir's skills / Lvl rises upon using Dazzling Flair or charge attack (Can't be removed)
  lvls.) deals by a lot through Emerald's Covenant. The charge attack of said weapon also gives 30% Skill DMG UpSkill DMG is boosted
  Strength: 30%Duration: 3.5 turnsApplied during the attack phase.
  On the next turn, it'll have 3 turns remaining. and 10% Skill DMG Cap UpMaximum amount of skill DMG that can be dealt per hit is boosted
  Strength: 10%Duration: 3.5 turnsApplied during the attack phase.
  On the next turn, it'll have 3 turns remaining., further increasing the skill damage output.
• Hollowsky Spear or Hollowsky Staff both grant conditional Supplemental DMGDMG dealt is supplemented
  that he can use due to his weapon proficiency.

Summon Synergy

Some notable summons that Grimnir (Valentine) can use are:

• Belial: Provides passive Supplemental DMGDMG dealt is supplemented
  as its sub-aura effect.
• Rose Queen (Summer): Has Supplemental DMGDMG dealt is supplemented
  and, upon 4★, Bonus DMGDeals bonus DMG for one-foe one-ally attacks
  .
• Owlcat: Provides Bonus DMGDeals bonus DMG for one-foe one-ally attacks
  should he be in the first or third position in the party.
• Halluel and Malluel: Applies EverbaneBoost to DMG taken / HP is lowered on every turn (Can't be removed)
  Local status effect on foes, another Supplemental DMGDMG dealt is supplemented
  source.